Non-innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides

2021 ◽  
Author(s):  
Alyah F. Chmiel ◽  
Oliver P. Williams ◽  
Colleen P. Chernowsky ◽  
Charles S. Yeung ◽  
Zachary K. Wickens
Keyword(s):  
Photoredox Catalysis ◽  
Aryl Chlorides ◽  
Parallel Reduction

scholarly journals Electro-mediated PhotoRedox Catalysis for Selective C(sp3)-O Cleavages of Phosphinates to Carbanions

2021 ◽  
Author(s):  
Xianhai Tian ◽  
Tobias Karl ◽  
Sebastian Reiter ◽  
Shahboz Yakubov ◽  
Regina de Vivie-Riedle ◽  
...  
Keyword(s):  
Radical Anion ◽  
Reductive Cleavage ◽  
Photoredox Catalysis ◽  
Structural Variations ◽  
Aryl Chlorides ◽  
Anion Form

We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp<sup>3</sup>)-O bonds of phosphinates to alkyl carbanions. As well as deoxygenations, olefinations are reported which are <i>E</i>-selective and can be made <i>Z</i>-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for a more intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp<sup>3</sup>)-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions i) tolerate aryl chlorides/bromides and ii) do not give rise to Birch-type reductions.

scholarly journals Potent Reductants via Electron-Primed Photoredox Catalysis: Unlocking Aryl Chlorides for Radical Coupling

2020 ◽  
Vol 142 (5) ◽  
pp. 2093-2099 ◽  
Author(s):  
Nicholas G. W. Cowper ◽  
Colleen P. Chernowsky ◽  
Oliver P. Williams ◽  
Zachary K. Wickens
Keyword(s):  
Photoredox Catalysis ◽  
Aryl Chlorides ◽  
Radical Coupling

Utilising excited state organic anions for photoredox catalysis: activation of (hetero)aryl chlorides by visible light-absorbing 9-anthrolate anions

2019 ◽  
Vol 215 ◽  
pp. 364-378 ◽  
Author(s):  
Matthias Schmalzbauer ◽  
Indrajit Ghosh ◽  
Burkhard König
Keyword(s):  
Excited State ◽  
Visible Light ◽  
Ground State ◽  
Organic Anions ◽  
Photoredox Catalysis ◽  
Aryl Chlorides

A novel photocatalytic concept based on photoexcitation of an organic anionic ground state catalyst for direct C–H (het)arylations using (het)aryl chlorides.

scholarly journals Electro-mediated PhotoRedox Catalysis for Selective C(sp3)-O Cleavages of Phosphinates to Carbanions

2021 ◽  
Author(s):  
Xianhai Tian ◽  
Tobias Karl ◽  
Sebastian Reiter ◽  
Shahboz Yakubov ◽  
Regina de Vivie-Riedle ◽  
...  
Keyword(s):  
Radical Anion ◽  
Reductive Cleavage ◽  
Photoredox Catalysis ◽  
Structural Variations ◽  
Aryl Chlorides ◽  
Anion Form

We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp<sup>3</sup>)-O bonds of phosphinates to alkyl carbanions. As well as deoxygenations, olefinations are reported which are <i>E</i>-selective and can be made <i>Z</i>-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for a more intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp<sup>3</sup>)-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions i) tolerate aryl chlorides/bromides and ii) do not give rise to Birch-type reductions.

Spin-Forbidden Excitation Enables Infrared Photoredox Catalysis

2020 ◽  
Author(s):  
Tomislav Rovis ◽  
Benjamin D. Ravetz ◽  
Nicholas E. S. Tay ◽  
Candice Joe ◽  
Melda Sezen-Edmonds ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Intersystem Crossing ◽  
Photoredox Catalysis ◽  
Infrared Irradiation ◽  
Triplet Excitation ◽  
New Family ◽  
Ir Light

We describe a new family of catalysts that undergo direct ground state singlet to excited state triplet excitation with IR light, leading to photoredox catalysis without the energy waste associated with intersystem crossing. The finding allows a mole scale reaction in batch using infrared irradiation.

Generation of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage–Independent Activation of Strong C–O Bonds

2018 ◽  
Author(s):  
Erin Stache ◽  
Alyssa B. Ertel ◽  
Tomislav Rovis ◽  
Abigail G. Doyle
Keyword(s):  
Carboxylic Acids ◽  
Functional Groups ◽  
Single Step ◽  
Direct Access ◽  
Photoredox Catalysis ◽  
Acyl Radical ◽  
Synthetic Strategy ◽  
Acyl Radicals ◽  
Benzyl Radicals ◽  
Aliphatic Carboxylic Acids

Alcohols and carboxylic acids are ubiquitous functional groups found in organic molecules that could serve as radical precursors, but C–O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen centered nucleophile. We first show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H-atom trapping to afford the deoxygenated product. Using the same method, we demonstrate access to synthetically versatile acyl radicals which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radical cyclizations to forge new C–O, C–N and C–C bonds in a single step.

Regioselective C3-H Trifluoromethylation of 2H-Indazole Under Transition-Metal-Free Photoredox Catalysis

2019 ◽  
Author(s):  
Arumugavel Murugan ◽  
Venkata Nagarjuna Babu ◽  
Nagaraj Sabarinathan ◽  
Sharada Duddu. S
Keyword(s):  
Transition Metal ◽  
Visible Light ◽  
Practical Approach ◽  
Hypervalent Iodine ◽  
Radical Mechanism ◽  
Photoredox Catalysis ◽  
Metal Free

Here we report a visible-light-promoted metal-free regioselective C3-H trifluoromehtylation reaction that proceeds via radical mechanism and which supported by control experiments. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the present trifluoromethylation reaction and synthesis of a library of trifluoromethylated indazoles.

Chiral Mn(III) Salen Complex Immobilized on CuFe2O4@SiO2-NH2 NPs: A Cheap and Efficient Catalyst for N-arylation of Aryl Halides and Phenylboronic Acid Under Mild Conditions

2020 ◽  
Vol 17 (11) ◽  
pp. 857-863
Author(s):  
Mohammad Ali Nasseri ◽  
Seyyedeh Ameneh Alavi ◽  
Milad Kazemnejadi ◽  
Ali Allahresani
Keyword(s):  
Phenylboronic Acid ◽  
Significant Loss ◽  
Aryl Halides ◽  
Coupling Reactions ◽  
Efficient Catalyst ◽  
Aryl Chlorides ◽  
Mild Conditions ◽  
Cross Coupling Reactions ◽  
Salen Complex ◽  
Ft Ir

A convenient and efficient chiral CuFe2O4@SiO2-Mn(III) Ch.salen nanocatalyst has been developed for the C-N cross-coupling reactions of aryl halides/ phenylboronic acid with N-heterocyclic compounds in water and/or DMSO under mild conditions. The catalyst could be applied for the N-arylation of a variety of nitrogen-containing heterocycles with aryl chlorides, bromides, iodides and phenylboronic acid under mild conditions. Moderate to good yields were achieved for all substrates. The structure of catalyst was characterized using various techniques including FT-IR, FE-SEM, EDX, XRD, TEM and TGA. The catalyst can be simply recovered and reused for several times without significant loss of activity.

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